Latest XPRIZE competition takes on ocean acidification

$2 million awaits designers of pH sensors that can gather the data we need.

Environmental problems can often seem intractable, not offering an obvious place for anyone to roll up their sleeves and make a significant difference. But the XPRIZE Foundation is now offering people the chance to bring home a considerable cash prize for solving an environmental challenge. All you need is the ability to develop a better pH sensor for monitoring ocean acidification and you can end up having a personal impact and a wad of cash.

The XPRIZE Foundation has been organizing competitions to spur technological innovation since Peter Diamandis put up $10 million for a successful sub-orbital launch of a privately built, manned spacecraft in 1996. (The prize was won in 2004 by Burt Rutan’s SpaceShipOne.)

In 2010, environmental advocate Wendy Schmidt donated $1.4 million for a competition to build a better oil cleanup system following the Deepwater Horizon oil spill in the Gulf of Mexico. During the XPRIZE tests, the winning team demonstrated that they could recover oil over three times faster than the best technology in use by industry. Schmidt was so pleased with the results that she is putting up $2 million to help address a global marine environmental threat: ocean acidification.

Ocean acidification is caused by increasing atmospheric CO­2, which dissolves into ocean water. This process lowers the pH of ocean water and decreases the concentration of carbonate ions—making it harder for organisms to build calcium carbonate shells.

The pH data we have for the world’s oceans have been hard-won. Temperature and salinity measurements are routinely made by an army of autonomous ARGO floats drifting around the ocean. But pH measurements have to be made carefully in a lab setting. That means that all our data comes from work aboard research vessels or at the research stations that carry out long-term monitoring. A large expansion of this sort of monitoring is a prohibitively labor-intensive and costly proposition.

Most existing pH instruments rely on a couple different basic designs. Some perform potentiometric measurements using a pair of electrodes (like common handheld pH meters). These are great for some applications, but most aren’t accurate enough to detect ocean acidification. A pair of researchers from the Monterey Bay Aquarium Research Institute and the Scripps Institution of Oceanography recently developed a variation on this theme that is much more accurate, but it can only be used near the surface.

The design commonly used for ocean research relies on a spectrophotometer—that is, it precisely measures the color of a pH indicator dye added to the water sample. This technique can be extraordinarily accurate, but it can't easily be deployed in a handy, compact device. (The most obvious problem is the need to replenish the supply of indicator dye.)

But any design—whether it’s one of these two or a completely different technology that hasn’t yet made it off the drawing board—could win the XPRIZE, provided it can beat the competition. “It’s absolutely wide open,” Bunje said. “That’s where XPRIZE is completely solution agnostic. We’re not here to solve the problem, we’re here to set the challenge and let the really smart people solve it.”

Entrants will be judged on five criteria: accuracy, precision (repeatability), stability (many sensors drift into error over time), cost, and ease of use. There are actually two separate prizes— $1 million each—that will be awarded based on a subset of these criteria. One purse will go to the team with the best accuracy, precision, and stability, and the other will go to the team whose solution scores best on cost and ease of use.

Judging will take place over three phases of the competition. The first trial will take place in a controlled lab setting. Each team’s device will continuously monitor pH in a tank for three months. The best performers will move on to a month-long field test in Washington’s Puget Sound. The pH of those waters is extremely variable, providing a different kind of challenge. Before beginning this phase, the teams will choose whether they’re going for one or both of the prizes. The top 5 teams pursuing the accuracy prize will advance to the final trial—a five-day cruise in the Pacific. They will have to repeatedly measure pH profiles from the surface down to a depth of 3 kilometers, a full kilometer deeper than any existing sensor is rated.

The end result will hopefully be a device that could be deployed for scientific research, greatly increasing our monitoring of ocean pH around the world. But Bunje also envisions a wider range of potential users. “There’s anybody from aquaculture firms and shellfish hatcheries to developing world marine managers and citizen scientists that could capitalize on the opportunity to monitor ocean pH in localized habitats, for instance. It’s that sort of democratization of technology that we hope will begin to catalyze a growth both in enthusiasm for monitoring, and markets in things like ocean services, forecasting, and data services.”